80 IOWA ACADEMY OF SCIENCES. 



Koch's laboratory in Berlin with this germ, who became sick and had the symp- 

 toms of genuine cholera, the experiments of Ferran, Koch, Gamaleia and others 

 with guinea pigs, leave no doubt as to the causal connection of organism and 

 Asiatic cholera. It is generally recognized now as the cause of this disease. There 

 are many apparent anomalies as shown in the distribution of cholera and von 

 Pettenkofer's "groundwater theory," which are fully set forth in Dr. Shakespeare's^* 

 splendid monograph on cholera. If the contagious nature of the disease and the 

 biological questions are taken into account, these conditions can be accounted for. 

 The history and spread of this disease all show how important it is to take heed of 

 sanitary conditions. It shows that the disease spreads most rapidly where effluvia 

 and excreta contaminate the water; food, too, may be an important item. That old 

 habit of using sewage water to sprinkle over vegetables, or the use of night soil 

 for growing vegetables is an extremely dangerous thing. 



WATER ANALYSIS. 



This brings up the question of making bacteriological analysis of water and in 

 this connection we may discuss typhoid fever. It is a well recognized fact that 

 this disease is caused largely through the use of water and food that contains the 

 active virus. The causal connection of the Koch Eberth bacillus and typhoid 

 fever is generally conceded, but the proofs are not as certain as in some of the other 

 contagious diseases, since bacteriologists have not been successful in producing' 

 typical typhoid fever in lower animals. This is not surprising since there are no 

 animals that take this disease as man does. But it is pathogenic to mice and 

 lower animals. A study of the typhoid fever bacillus is not an easy matter since 

 there are several closely related species like Bacillus coU-communis which norm- 

 ally occur in the colon of man, other forms of this species occur in dysentery, 

 cholera infantum, catarrhal enteritis, gastroenteric catarrh, peritonitis and other 

 diseases. Other germs of this general character are quite common in decaying 

 substances, and some are pathogenic. The hog cholera germ, swine plague; the 

 Bacillus coli-comniunis are well known for their pathogenic properties. Dr. Theo- 

 bold Smith"' has, however called attention to some important characters of the 

 germs when grown in the fermentation tube, which enables us to separate coli- 

 communius from nearly allied forms. 



It has long been customary to regard a chemical analysis of water sufficient to 

 determine whether water is good for drinking purposes or not. There seems how- 

 ever, to be a rapidly growing tendency to move along biological lines. I would not 

 underrate chemical analysis, it should go hand in hand with this biological work. 

 There are so many problems that the biologist cannot explain unless the chemist 

 is at his elbow. Dr. Stevens says: " It is perhaps enough to say that a chemist is not 

 of necessity a sanitarian, nor is his work the most important basis upon which a 

 sound or safe conclusion is built as to the proper hygienic value of water for potable 

 uses." Mr. Rafter'-" a well known sanitary engineer says: " Attention should be 

 called moreover to the general proposition that the chemical methods are so refined 

 in their nature that a slight error is liable to invalidate the results; whereas the 

 microscopic analysis has the advantage of making the bulk of the organic contam- 

 inating material visible to the sense of sight." The chemist can determine that 



««Report on cholera in Europe and I idia, pp. 945, with numerous charts and dia- 

 grams. Washington, Government Printing Office, 1890. 



69Centralbatt fur Bakteriologie and Parasitenkunde, Vol. XII, p. 367. 



740n the micro-organisms In Hemlock water. The quotation from Stevens Is taken 

 from this paper. 



